Process and arrangement for the incremental enrichment of deuterium and/or tritium in a material suitable for the isotope exchange of deuterium and/or tritium with hydrogen

ABSTRACT

A process for the incremental enrichment of deuterium and/or tritium in a material which is suitable for the isotope exchange of deuterium and tritium with hydrogen, and an arrangement for the implementation of the process. The process and arrangement for the enrichment of deuterium and/or tritium in water which, in addition to a high transport speed for the molecules which participate in the isotope exchange, evidences a high enrichment factor for each enrichment stage and a high yield, so that at a relatively small number of stages and low energy consumption there is attainable an overall high degree of enrichment. For each enrichment stage, water containing deuterium and/or tritium is introduced into a carrier gas flow, reduced and set to a hydrogen (H 2 ) partial pressure of maximally 100 mbar. Subsequent thereto, the carrier gas flow is conveyed along the primary side of an exchange wall which is suitable for the permeation of hydrogen, along the secondary side of which there flow a further carrier gas flow which contains a material adapted for the isotope exchange of deuterium and tritium with hydrogen in the gas phase thereof. The hydrogen isotopes deuterium and/or tritium which permeate through the exchange wall, after the isotope exchange, are bonded with the material in reaction product.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a process for the incrementalenrichment of deuterium and/or tritium in a material which is suitablefor the isotope exchange of deuterium and tritium with hydrogen, as wellas to an arrangement for the implementation of the process.

The formation of deuterium, D₂, and tritium, T₂, is not only ofsignificance for the nuclear fusion technology, in which deuterium andtritium serve as "fuels" and which are fused to helium under the outputof energy. There is also known the utilization of deuterium in nuclearreactors moderated with heavy water, in which D₂ O is employed as themoderator. Tritium is applied in the production of the luminescentpigments, for example, for luminescent paints, as well as for componentsin the gas filling of fluorescent lighting tubes and in the productionof lightning arresters. Moreover, tritium is employed as a target forbeam modulation in particle accelerators. In addition thereto, tritiumserves for the marking of chemical compounds, for example, in the fieldof biochemistry.

Deuterium is contained in basic hydrogen and in water with 0.015 At %;in the hydrogen overwhelmingly as HD, in water in the form of HDO.Tritium is present in basic hydrogen only in disappearingly lowconcentrations; however, it is obtained for instance, as a byproductduring the operation of nuclear reactor installations, particularly inheavy water reactors and high-temperature reactors, as well as duringthe reconditioning of spent nuclear fuel elements. Inasmuch as tritiumis radioactive and is directly taken up in the bio-cycle in the form ofHTO, even minute quantities of tritium which are produced during theneutralizing of nuclear reactor installations, cannot remain unnoticed.For the neutralizing of the encountered tritium it is known to enrichand bond tritium in water.

2. Discussion of the Prior Art

Different processes are known for the enrichment of deuterium or tritiumin hydrogen and water hereby having reference to K. M. Mackay et al"Deuterium and Tritium", in "Comprehensive Inorganic Chemistry", Volume1, Pergamon Press, New York, 1973, pages 77 through 84; as well as NUKEM500, "Herkunft, Handhabung and Verbleib von Tritium" RSI-510 321/196-SR165, Febraury 1980. For example, an enrichment is achieved through thedistillation of liquid hydrogen at a temperature of about 23° K. orthrough the distillation of water at 70° C. and under a vacuum.Hydro-electrolysis is known as a process with a high separating factor;thereof, in the same manner as with the distillation of hydrogen, inaddition to meeting increased safety demands (high degree of sealing,explosion protection), there must also be covered a significant energydemand with regard to the enriched quantity of deuterium or tritium. Thelast is, above all, the instance inasmuch as it is necessary to commencewith a low initial concentration of deuterium and tritium in water. Inaddition thereto, also known are processes in which deuterium andtritium are enriched in water through an isotope exchange in the liquidphase; referring to H. J. Fiek et al, "Tritium-Anreicherung durchIsotopenaustausch zwischen Wasserstoff und Wasser, mittels hydrophobenKatalysators fuer die Kernbrennstoff-Wiederaufbereitung",Chem.-Ing.-Techn. 52, 1980, pages 892 through 895. However, the exchangespeeds in such a process are relatively slow, even with the utilizationof catalysts. Moreover, currently known catalysts evidence a highsusceptibility to disruption.

A heavy water recovery through the utilization of ammonia, NH₃, ismentioned in the KWU-Report, No. 32, April 1980, page 9. The heavy wateris recovered through a monothermal ammonia-hydrogen isotope exchange. Insuch a process, disadvantageous is the high energy demand, which isparticularly generated during the employed electrolytic ammonia fission,and which is required for the subsequent ammonia synthesis. Also theyield for the exchanged deuterium remains low during an ammonia-waterisotope exchange.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide aprocess for the enrichment of deuterium and/or tritium in water which,in addition to a high transport speed for the molecules whichparticipate in the isotope exchange, evidences a high enrichment factorfor each enrichment stage and a high yield, so that at a relativelysmall number of stages and low energy consumption there is attainable anoverall high degree of enrichment.

In accordance with an inventive process of the above mentioned type, foreach enrichment stage, water containing deuterium and/or tritium isintroduced into a carrier gas flow, reduced and set to a hydrogen (H₂)partial pressure of maximally 100 mbar. Subsequent thereto, the carriergas flow is conveyed along the primary side of an exchange wall which issuitable for the permeation of hydrogen, along the secondary side ofwhich there flow a further carrier gas flow which contains a materialadapted for the isotope exchange of deuterium and tritium with hydrogenin the gas phase thereof. The hydrogen isotopes deuterium and/or tritiumwhich permeate through the exchange wall, after the isotope exchange,are bonded with the material in the reaction product. Employed as thecarrier gas on the primary side of the exchange wall is a gas which willnot disruptively influence the reduction of the water, and on thesecondary side a gas which will not disruptively influence the isotopeexchange, for instance, an inert gas such as helium or argon. For theisotope exchange, the carrier gas flow on the secondary side is toconvey along a quantity of material per unit of time which, at least forthe concentration drop between the primary and secondary sides of theexchange wall required for the permeation of deuterium and/or tritium,is greater than the hydrogen quantity per unit of time flowing along theprimary side in the carrier gas flow divided by the equilibrium weightconstants for the reaction equation which is determining for the isotopeexchange. With respect to concentration drop there is hereby to beunderstood the ratio of the partial pressure of the molecules HD or HTon the primary side with respect to the partial pressure of the samemolecules HD or HT on the secondary side of the exchange wall. When inthe added material there are to be concurrently enriched deuterium andtritium, then in this instance, for the determination of the minimummaterial quantity to be introduced there are to be considered thepresently smaller equilibrium weight constants of the reactionsdeterminative for the isotope exchange of deuterium with hydrogen ortritium with hydrogen. The quantity material which is to be introducedinto the carrier gas flow on the secondary side is, however, to bealways measured smaller than in the carrier gas flow along the primaryside of the exchange wall after reduction of the water per unit of time.The reaction products which are produced through the isotope exchangewith the material are conveyed off by the carrier gas from the secondaryside of the exchange wall.

In an advantageous manner, in the inventive process the isotope exchangetakes place primarily on the surface of the exchange wall so that, athigh transport speeds of the molecules along the wall, as they occurduring the gas phase, there is propagated the desired isotope exchange.Hereby, the exchange wall through which there permeate the hydrogenisotopes, serves concurrently for a separation of between the low andhighly enriched gas fractions. The exchange wall evidences a catalyticeffect for the atomization of the molecules. Through the setting of ahydrogen (H₂) partial pressure of maximally 100 mbar in the carrier gasflow on the primary side, the permeation through the exchange wall canalso be maintained over lengthier operating periods. The energy requiredfor each enrichment stage is relatively low. For the heating of thecarrier gas flow there can be utilized the exothermic reaction of thewater which is introduced into the carrier gas flow.

Suitable as material for the isotope exchange with thehydrogen-deuterium-tritium mixture permeating through the exchange wallis, above all, water or steam. For the isotope exchange, in addition toor in lieu of the preferably employed water, there can also be utilized,for example, ammonia, NH₃, or hydrogen sulfide, H₂ S. The material whichis added on the secondary side of the exchange wall for the isotopeexchange then contains overwhelmingly the hydrogen isotope H so that forhydrogen, in contrast with the hydrogen isotopes deuterium and/ortritium which are to be bonded, there is produced a concentrationequilibrium on both sides of the exchange wall.

During the addition of water there is formed HTO and HDO, for example,from HT and HD, pursuant to the reactions

    HT+H.sub.2 O⃡HTO+H.sub.2                       ( 1)

    HD+H.sub.2 O⃡HDO+H.sub.2                       ( 2)

wherein through an increase of the H₂ O partial pressure in the carriergas there is propagated the transition of HT into HTO and of HD intoHDO. For the determination of the minimum water quantity which is to beintroduced into the carrier gas flow on the secondary side, there mustbe considered the equilibrium weight constants of both reactions; forthe enrichment of tritium the equilibrium weight constants of theabove-mentioned equation (1), for the enrichment of deuterium theequilibrium weight constants of the above-mentioned equation (2). Whendeuterium as well as the tritium are enriched in water, in this instancethere would be determinative the smaller equilibrium weight constants ofthe equations, which determine the isotope exchange. The water quantitywhich is introduced into the carrier gas flow on the secondary side is,however, always to be held lower as the hydrogen quantity contained inthe carrier gas flow on the primary side, in order to attain anenrichment. In the employment of water as the material for the isotopeexchange in the carrier gas flowing on the secondary side, set as theoperating temperature for each exchange stage is a temperature withinthe temperature range of between 100° and 300° C. Within thistemperature range, the equilibrium weight constants for the isotopeexchange with steam evidence satifactory values. The equilibrium weightconstant for the isotope exchange of tritium with hydrogen at 120° C.,for example, consists of about K=3.6, and for deuterium with hydrogen atthe same temperature of about K=2.46. Should, for this instance,deuterium and tritium be enriched in water, then for the determinationof the minimum water quantity which is to be to the carrier gas flow onthe secondary side, the equilibrium weight constant for the isotopeexchange between deuterium and hydrogen is determinative.

Hydrogen, H₂, is contained at the same partial pressure in the gas onthe primary side as well as on the secondary side of the exchange wall.Thus it is not removed from the carrier gas flow on the primary side. Onthe secondary side of the exchange wall there are formed the reactionproducts set forth on the right side of the above-mentioned equations(1) and (2). The reaction products are conducted off by the carrier gason the secondary side. The carrier gas then flows into the subsequentexchange stage as the carrier gas flow on the primary side thereof. Inthis exchange stage, the reaction products, upon the utilization ofwater for isotope exchange, in essence, with deuterium and/or tritiumenriched water, are reduced in the same manner as in the firstenrichment stage, so that for the hydrogen in the carrier gas there isagain set a partial pressure of maximally 100 mbar. The carrier gas isthen conveyed along the primary side of the exchange wall of the furtherenrichment stage. The hydrogen isotopes deuterium and/or tritiumpermeate to the secondary side of the exchange wall and already herereact extensively on the surface of the exchange wall through isotopeexchange with the material which is conveyed along this side of theexchange wall within the carrier gas. The reaction products are conveyedoff by the carrier gas.

In further embodiments of the inventive process, the carrier gas flow onthe primary side of the exchange wall and the carrier gas flow on thesecondary side of the exchange wall are conducted in counterflow inorder to attain the concentration differences on both sides of theexchange wall which are adequate for permeation. As the carrier gas onthe secondary side there is preferred the carrier gas also flowing onthe primary side of the exchange wall. The carrier gas, in this case,can be withdrawn in an advantageous manner from the carrier gas flowwhich flows along the primary side of the exchange wall, as soon asafter permeation of the deuterium and/or tritium this flows off theexchange wall. A portion of the carrier gas flowing on the primary sideis withdrawn and, with the addition of material suitable for isotopeexchange, is conducted to the secondary side of the exchange wall.Through this measure there is achieved, concurrently, a pressureequilibrium on both sides of the exchange wall, up to a slight vacuum onthe secondary side which essentially corresponds to the pressure losswhich is produced on the primary side of the exchange wall upon thethroughflow of the carrier gas through the exchange installation, aswell as a temperature equilibrium between the primary and secondary sideof the exchange wall. The material which causes the isotope exchange isintroduced so timely into the branched off partial gas flow of thecarrier gas that upon inflow of the gas to the secondary side of theexchange wall, there is present a sufficient concentration drop relativeto the carrier gas on the primary side of the exchange wall. It isadvantageous that the secondary carrier gas flow, subsequent theaddition of the material which reacts with the hydrogen isotopes, beconducted prior to flowing through of the secondary side of the exchangewall over a catalyst which accelerates the reaction between the addedmaterial and the hydrogen isotopes, for example, overplatinum-impregnated activated charcoal. Such catalysts, and thosecatalysts listed in the above-mentioned article in Chem.-Ing. Technik52, 1980, page 892, can also be employed on the secondary side of theexchange surface for the acceleration of the isotope exchange. In orderto yet produce the required concentration drop prior to entry of thebranched-off carrier gas into the secondary side of the exchange wall,the branched-off partial flow can also be conducted over a metal oxidebed, in which the hydrogen which is carried along by the carrier gas isoxidized, before the material which causes the isotope exchange is addedto the partial gas flow.

It is advantageous to undertake the setting of the desired partialpressure in each enrichment stage subsequent to the reduction of thewater which is contained in the carrier gas flow on the primary side.This is particularly the case when the water-containing gas is conveyedfor reduction through a metal bed, for example, through an irongranulate or copper granulate bed, in which there are producedcorresponding pressure losses during through-flow. For acceleration ofthe desired atomization of the reduction products, the carrier gas flowon the primary side, prior to contact with the exchange wall, is yetconducted over a catalyst, in particular over metal hydride, for exampleUH₃, UD₃. The catalyst can be present as a solid bed catalyst or as animpregnation on the primary side of the exchange wall.

When deuterium and/or tritium are enriched in the carrier gas in wateron the secondary side, it is advantageous to introduce water into thecarrier gas flow on the secondary side, whose deuterium and/or tritiumcontent corresponds to the content of the deuterium and/or tritium whichis evident in the water introduced in the first enrichment stage intothe carrier gas flow on the primary side.

Suitably, the carrier gas flow which flows off the primary side of theexchange wall, occasionally after withdrawal of a partial flow which isconducted to the secondary side of the exchange wall, subsequent tooxidation of the hydrogen carried along by the carrier gas and theseparation of the thereby formed water, is reconveyed in a closedcircuit to the inlet of the enrichment stage. In order to have to assumeonly minor pressure losses for the separation of the hydrogen from thecarrier gas flow on the primary side, the carrier gas flow is preferablyconducted along a further exchange wall which is adapted for thepermeation of hydrogen, on the secondary side of which there is presentan oxidizing agent for oxidation of the hydrogen which permeates throughthe exchange wall. As oxidizing agents there are suited, above all,oxygen or metal oxides, such as copper oxide or iron oxide. The waterwhich is formed as the reaction product is also conducted away from thesecondary side of the exchange wall by the carrier gas and separated outthrough condensation. A portion of this water can be utilized on thesecondary side of the exchange wall as the material which is suitablefor the isotope exchange. In this instance however for the recovery ofdeuterium and/or tritium only the half of the quantity of water whichcontains deuterium and/or tritium is usable which, in the employment ofthe output water is also usable as material for the isotope exchange onthe secondary side of the exchange wall. As output water there is hereinidentified the water containing the deuterium and/or tritium which, inthe first enrichment stage, is conveyed into the carrier gas flowflowing on the primary side of the exchange wall.

In a further embodiment of the invention provision is made in that atleast a portion of the carrier gas which flows off from the primary sideof the exchange wall is employed in the subsequent stage for the settingof the hydrogen partial pressure, after separation out of the hydrogencarried along therewith. The hydrogen-free carrier gas is suitablyconveyed in a closed flow circuit in which the conveying aggregates forthe carrier gas flow are presently arranged in the hydrogen-free portionof the flow circuit.

BRIEF DESCRIPTION OF THE DRAWINGS

Hereinbelow there is elucidated in greater detail the inventive processand an arrangement for the implementation of the process on the basis ofexemplary embodiments. FIG. 1 of the drawings schematically illustratean installation for the enrichment of deuterium and/or tritium in wateror steam, with at least two enrichment stages to which, however, inaccordance with the desired degree of enrichment, there can be connectedadditional enrichment stages by basically the same construction; and

FIG. 2 illustrates a portion of the installation including the condenserand reduction chamber section.

DETAILED DESCRIPTION

In the drawings, installation components which are constructedidentically or the same manner and which are employed in each of theenrichment stages, are identified by the same reference numerals. Forrecognition of the individual enrichment stages, these referencenumerals are provided with suffix letters for the installationcomponents which characterize the therewith associated enrichment stage.For the first enrichment stage the reference numerals include the suffix"a", for the second enrichment stage the suffix "b", and so forth.

As can be ascertained from the drawings, and particularly FIG. 1, eachenrichment stage of the installation includes connected in sequence inthe flow direction 1a, 1b, of a carrier gas flow conveyed in an inletconduit 2a, 2b, 2c for the third enrichment stage, not shown in thedrawings, a reduction chamber 3a, 3b, for water which is contained inthe carrier gas flow, which in the first enrichment stage is introducedthrough an inlet conduit 4 having a throughflow regulator 5 into thecarrier gas flow, an exchange installation 6a, 6b for isotope exchangebetween deuterium and/or tritium and hydrogen, as well as an oxidationchamber 7a, 7b for the hydrogen which is carried along by the carriergas flow from the exchange installation 6a, 6b. Each exchangeinstallation 6a, 6b is constructed similar to a heat exchanger. Thus,there can be utilized apparatuses, for example, of the type of a bundledtube heat exchanger in which, for instance, there are employed coiledtubes, or a type of plate heat exchangers with flat or corrugated walls.The structural units which otherwise serve for heat exchange, in theexchange installations provide exchange walls for the permeation of thehydrogen isotopes. In the drawings, the exchange walls are shown merelyschematically and designated with reference numerals 8a, 8b. Inconformance with their purpose, the exchange walls are constituted of amaterial with high degree of permeability for hydrogen, in the exemplaryembodiment the exchange walls are constructed of palladium orpalladium-silver (approximately 75% Pd, 25% Ag). However, also adaptedas material for the exchange walls are palladium-coated Nb, Ta, V aswell as alloys of these metals or also interconnected metal coatings.

Into each of the exchange installations 6a, 6b after reduction in thereduction chamber 3a, 3b of the water which is introduced together withthe carrier gas, a hydrogen/deuterium/tritium gas mixture is introducedinto the carrier gas flow. The hydrogen partial pressure in the carriergas which is provided for the permeation of the hydrogen isotopes is setsubsequent to the reduction of the water by the introduction of furthercarrier gas through carrier gas conduit 9a, 9b with through-flowregulators 10a, 10b and 11. In order to maintain throughout optimumconditions for the permeation of the hydrogen isotopes through theexchange wall even over lengthier operating periods, the partialpressure for hydrogen is set so as not to exceed 100 mbar. As theoperating temperature, there is provided in the exchange installation atemperature within the temperature range of about 100° to 300° C. Forthe heating of the carrier gas there serves a heater 12a, 12b which iscontrolled by a thermostat 13a, 13b in the exchange installation 6a, 6b.The heating of the carrier gas is effected through the utilization ofthe heat generated during the reduction of the water in the reductionchamber 3a, 3b as a result of exothermal processes.

In order to not inhibit the transport of the molecules to the surface ofthe exchange wall, and for limiting the quantity of the carrier gaswhich is to be circulated it is purposeful to operate at a pressure ofbetween 1 and 5 bar. At a higher pressure, required in the exchangeinstallation are larger exchange surfaces, as well as measures for thesealing of the installation.

The carrier gas is conducted within flow spaces or chambers 14a, 14b,which are respectively arranged on the primary side of the exchange wall8a, 8b, along the exchange wall. On the secondary side of the exchangewall 8a, 8b, a further carrier gas flow flows through the exchangeinstallations in counterflow direction 15a, 15b relative to that of thecarrier gas on the primary side. The carrier gas on the secondary sideis introduced through a gas conduit 16a, 16b into the flow spaces 17a,17b of the exchange installation. In the illustrated embodiment, heliumis provided as the carrier gas on the primary side as well as on thesecondary side. However, other inert gases can be employed as thecarrier gas, in particular argon.

In the flow space 17a, 17b of the exchange installation 16a, 16b, ineach exchange stage water or steam is contained in the carrier gas,which is introduced into the carrier gas flow by means of a water orsteam conduit 18a, 18b having throughflow regulator 19a, 19b therein.When water is introduced into the carrier gas flow, then this must bevaporized still ahead of the entry of the carrier gas into the flowspace 17a, 17b on the secondary side of the exchange installation. Thesteam reacts in the flow space 17a, 17b already extensively on thesurface of the exchange wall with the hydrogen isotopes deuterium and/ortritium which permeate from the primary side of the exchange wall 8a, 8bthrough isotope exchange. Deuterium and/or tritium leave the surface ofthe exchange wall on the secondary side overwhemingly as HDO and D₂ O,or relatively HT on T₂ O molecules, and only in a neglible lowproportion as HD, D₂, or HT, T₂ molecules. The quantity of water whichis to be conveyed along for this purpose by the carrier gas flow perunit of time, pursuant to the mass conversion law, is to be dimensionedcorrespondingly larger by at least by the concentration drop requiredfor the permeation of deuterium and/or tritium between the primary andsecondary sides of the exchange wall 8a, 8b, than the hydrogen (H₂)quantity per unit of time flowing on the primary side in the inert gasflow, divided by the equilibrium weight constants of the reactionequation determinative of the desired isotope exchange between deuteriumand/or tritium. The quantity of water is, however, to be set smallerthan the hydrogen quantity conducted along per unit of time in thecarrier gas flow on the primary side of the exchange wall, in order toachieve an enrichment. Within these limits, the quantity of water isvariable, whereby the concentration drop which propagates the permeationbetween the primary and secondary sides of the exchange wall is thehigher, the more water is introduced into the carrier gas flow. There isthus required an optimization, since with an increasing quantity ofwater there will drop off the attainable degree of enrichment. Thereaction products which are obtained during isotope exchange areconveyed off by the carrier gas from the secondary side of the exchangewall.

For the formation of the carrier gas flow on the secondary side of theexchange wall, in the illustrated embodiment a portion of the carriergas flowing off from the primary side of the exchange wall is branchedoff in an exhaust discharge gas conduit 20a, 20b. Serving for theadjustment of the partial gas flow are throughflow regulators 21a, 21bin the outlet gas conduit 20a, 20b as well as throughflow regulators22a, 22b which are provided in the gas conduit 16a, 16b, ahead of theconnection of these with the exhaust gas conduit 20a, 20b. Theadjustment of the branched-off partial gas quantity influences theconcentration of the steam in the carrier gas flow on the secondaryside. From the bypass factor, which indicates the relationship of themass throughput of the carrier gas on the secondary side of the exchangewall relative to the mass throughput of the carrier gas on the primaryside, the steam concentration which is to be set is dependent inverselyproportional. The steam concentration, (H₂ O), in the carrier gas flowon the secondary side is obtained during enrichment of deuterium withconsideration given to the previously-mentioned reaction equation (2)and a yield of almost 100% from ##EQU1## wherein ξ_(D) =concentrationdrop off HD (HD partial pressure on the primary side relative to HDpartial pressure on the secondary side),

[H₂ ]=hydrogen concentration in the carrier gas flow on the primaryside,

α=bypass factor (carrier gas-mass throughput on the secondary siderelative to the carrier gas mass through-put on the primary side,

K(₂)=equilibrium weight constants for the reaction equation (2).

The carrier gas flow which remains in the discharge conduit 20a, 20bsubsequent to the withdrawal of the partial gas flow, is introduced intothe oxidation chamber 7a, 7b, in which there is oxidized the hydrogen(H₂) which is still carried along by the carrier gas flow afterseparation of deuterium and/or tritium from thehydrogen/deuterium/tritium mixture. In this embodiment, the oxidationchamber 7a, 7b is contained analogous to the exchange installation 6a,6b and, in the same manner, incorporates exchange walls which aresuitable for the permeation of hydrogen. Along these exchange walls,which are merely schematically illustrated in the drawing and which areidentified by reference numerals 23a, 23b, the carrier gas flow isconducted on the primary side of the oxidation chamber within its inflow spaces 24a, 24b. The hydrogen permeates out of the carrier gasthrough the exchange walls 23a, 23b and is bound on the secondary sideof each exchange wall through oxidation. As the oxidation medium, in theembodiment, there is provided within the flow spaces 25a, 25b, a metaloxide bed 26a, 26b, for example, a granulate bed of copper oxide or ironoxide which, during reaction with the permeating hydrogen, is reducedwith the formation of water. The metal oxide bed 26a, 26b isrecognizable in drawing by the stippling of the flow spaces 25a, 25b.For the oxidation of the permeated hydrogen, each flow space 25a, 25bcan also have oxygen introduced thereto through an oxygen conduit 27a,27b with throughflow regulator 28a, 28b. In general, however, thehydrogen is oxidized in the oxidation chamber 7a, 7b on metal oxide orthrough the introduction of oxygen into the flow space 25a, 25b. Theoxidation chamber 7a, 7b with the exchange walls 23a, 23b affordsadvantages above all, with respect to the flow resistances which are tobe considered during the flowing through of the carrier gas. These areof minor significance, when the oxidation of the hydrogen carried alongby the carrier gas can also be attained, for example, through conductionof the carrier gas on the primary side into a metal oxide bed. The waterformed thereby is conducted off.

In the illustrated embodiment, connected to the oxidation chamber 7a, 7bfor the infeed and outlet of the carrier gas which conveys off of theoxidation products from the secondary side of the exchange wall 23a, 24bare, on the one hand, an inlet conduit 29a, 29b for carrier gas and adischarge conduit 23a, 30b for the carrier gas which is charged with thereaction products. The carrier gas flow on the secondary side of theexchange wall is conveyed in counterflow to the carrier gas flowing onthe primary side of the exchange wall. The outlet conduit 30a, 30bconnects into a condenser 31a, 31b in which the carried along water iscondensed and withdrawn through a condensate conduit 32a, 32b. In theembodiment, the condensate conduit 32a, 32b is connectable with water orsteam conduit 18a, 18b. By means of the through flow regulator 33a, 33bthere can be readily regulated the quantity of water which isintroduceable from the condenser 31a, 31b into the water or steamconduit 18a, 18b.

When the desired enrichment of deuterium and/or tritium is achievedthrough isotope exchange in a plurality of sequentially connectedenrichment stages (n-times), as shown in FIG. 2, then the carrier gaswithdrawn from the last enrichment stage on the secondary side of theexchange wall, is introduced through an outlet conduit 34 into acondenser 35. In the condenser 35 there is condensed the water which isenriched with deuterium and/or tritium, and discharged through thecondensate conduit 36. For the formation of an enrichedhydrogen/deuterium/tritium gas mixture, a connecting conduit 38 isconnected to the outlet conduit 34, which also leads to a reductionchamber 37. Thus, after the closing of a valve 39 at the inlet to thecondenser 39 and after the opening of a valve 40 in the connectingconduit 38, the carrier gas can be introduced into the reduction chamber37 in which, for example, in a metal granulate bed which reduces thewater, there is formed a hydrogen/deuterium/tritium gas mixture which ishighly enriched with deuterium and/or tritium, and which isdischargeable through a gas conduit 41.

The formed highly enriched water, or the formedhydrogen/deuterium/tritium gas mixture, for further enrichment and forrecovery of deuterium and/or tritium can be conducted, for example, toinstallations for water electrolysis or for catalytic isotope exchange,for example, to isotope exchange on platinum. These known processes arepresently economically applicable, since it is possible to proceed froma product with a higher deuterium and/or tritium concentration.

When during operation of the described installation there is introducedinto a carrier gas flow which is conveyed to the first enrichment stageon the primary side of a total of 2.5 kg helium per second (this amountrelates to the total helium which is introduced into the exchangeinstallation 6a) through the inlet conduit 4, a quantity of water of0.56 kg/sec 2.02 t/h, then in the carrier gas on the primary side of theexchange wall 8a, at an almost complete conversion during the reductionof the water, there will set itself a hydrogen (H₂) partial pressure of46.2 mbar. The exchange wall of the first enrichment stage is sodesigned that approximately 97% of the deuterium and/or tritiumcontained in the carrier gas flow on the primary side will permeate tothe secondary side. In the exchange installation, on both sides of theexchange wall there is set an overall pressure of about 1 bar and atemperature of 120° C. These operating conditions are in effect for allenrichment stages of the enrichment installation. For the take up of thepermeated hydrogen isotopes, there flows along the secondary side of theexchange wall a carrier gas flow of 0.25 kg/sec of helium (bypass factorof the first enrichment stage α_(a) =0.1). The carrier gas flow containsa quantity of water of 0.277 kg/sec 1 t/h. When this water is entirelyremoved from the condensate water which is recovered in the oxidationchamber 7a, then in the first enrichment stage of the exchangeinstallation 6a, there is set in the carrier gas flowing off on thesecondary side, at a 97% yield for D₂ O and HDO, a partial pressure of66.4 μbar. Obtained thereby is a degree of enrichment S for deuterium inthe first enrichment stage of S=2. When the carrier gas on the secondaryside of the exchange wall has added thereto water with a deuteriumand/or tritium content for the isotope exchange, which corresponds tothe deuterium and/or tritium content of the water conveyed into thecarrier gas flow on the primary side of the first enrichment stage (thisdeuterium and/or tritium content is hereinbelow designated as outputquality), then there will set itself in the carrier gas on the secondaryside of the exchange wall, at the same yield for D₂ O and HDO, a partialpressure of 99.6 μbar. This corresponds to a degree of an enrichment ofS=3. For the tritium component in the carrier gas, under the samepreconditions, in the case of a utilization of condensate water from theoxidation chamber, there is achieved a degree of of S=3, with theutilization of water of output quality, a degree of enrichment of S=4.As degree of enrichment there is hereby to be understood the ratio ofdeuterium and/or tritium partial pressure, (D) or (T), relative to theoverall partial pressure of the hydrogen isotopes at the output on thesecondary side of the exchange installation of the "i" exchange stage,designation A_(i), to the deuterium tritium partial pressure (D) or (T),relative to the overall partial pressure of the hydrogen isotopes at theinput on the primary side of the exchange installation of the firstenrichment stage, designation Ao. As the degree of enrichment there isthus obtained for ##EQU2##

In the calculation of the partial pressure for deuterium and tritium inthe first enrichment stage which is set through isotope exchange thereis commenced from a yield of 97%. To be understood as yield is thequantity of deuterium or tritium bound in water through isotope exchangein the carrier gas flow on the secondary side relative to the quantityof deuterium or tritium in the water introduced to the primary side ofthe first enrichment stage. The remaining 3% of the recoverabledeuterium or tritium remain in the carrier gas conveyed off on theprimary side and are conducted off in the oxidation chamber duringoxidation of the hydrogen.

From the first enrichment stage, a carrier gas flows to the secondenrichment stage with a quantity of water of 0.277 kg/sec 1 t/h. Thiswater is conveyed in the reduction chamber 3b into ahydrogen/deuterium/tritium gas mixture. Thereafter, through the additionof further carrier gas by means of the carrier gas conduit 9b connectingdownstream of the reduction chamber 3b, the carrier gas flow is set to2.5 kg helium/sec. Obtained therewith for the hydrogen (H₂) partialpressure is a value of 23.1 mbar, as well as, corresponding to thedegree of enrichment achieved in the first enrichment stage, a deuterium(D₂, HD) partial pressure of 6.64 μbar for the instance of an enrichmentwith condensate water from the oxidation chamber, relatively a deuterium(D₂, HD) partial pressure of 9.96 μbar for the enrichment with theutilization of water of output quality in the carrier gas on thesecondary side. In the same manner, the tritium content corresponds tothe degree of enrichment achieved in the first stage, whereby upon theutilization of condensate water there will set a lower partial pressure,and with the utilization of water of output quality, a higher partialpressure.

The exchange installation 6b of the second enrichment stage includes, inthe same manner as the exchange wall of the first enrichment stage, ameasured exchange wall 8b. The obtainable yield in the second enrichmentstage consists of 99%. For the formation of the carrier gas flow whichflows on the secondary side of the exchange wall 8b, in the secondenrichment stage there is set a bypass factor of α_(b) =0.05. Introducedinto this carrier gas flow on the secondary side is a quantity of waterof 0.15 kg/sec 0.54 t/h. When, for this purpose, there is employed acondensate water from the oxidation chamber 7b, then at the end of thesecond enrichment stage there is set for deuterium a degree ofenrichment of S_(D) =3.7; when the carrier gas flow on the secondaryside has introduced therein water of output quality, for the deuteriumthere is then obtained a degree of enrichment of S_(D) =6.59. For thetritium component there is obtained, in the second enrichment stage, adegree of enrichment of S_(T) =8.35 in the utilization of condensatewater from the oxidation chamber, if S_(T) =12.2 upon the utilization ofwater of output quality.

The carrier gas now flows to the exchange installation of the thirdstage with only a water quantity of 0.54 t/h. The exchange surface whichis required for the permeation of the hydrogen isotopes can hereby bereduced by about 30% at a yield rising to 99.5%. At a constant remainingcarrier gas flow of 2.5 kg helium/sec. and a bypass factor of α_(c)=0.05, there is introduced into the carrier gas flow which is conductedto the secondary side of the exchange wall of the third enrichmentstage, additionally 0.076 kg/sec 0.272 t/h of water. Obtained at theoutlet of third stage for deuterium is a degree of enrichment of S_(D)=7.35 upon the utilization of condensate water from the oxidationchamber; of S_(D) =14 with the utilization of water with output quality.For tritium there are obtained degrees of enrichment, under the samepreconditions, in the first instance of S_(T) =25, in the secondinstance of S_(T) =48.

In the seventh enrichment stage the quantities of water which are to becarried along in the carrier gas flow are now quite minute. The requiredexchange walls can hereby be so correlated that, during permeation ofthe hydrogen isotopes through the exchange wall, there are obtainableyields of approximately 100%. In the seventh exchange stage, the carriergas flow on the secondary side has introduced thereto only 17.1 kgwater/h. At the outlet of this stage there is obtained for deuterium adegree of enrichment of S_(D) =118 upon the utilization of condensatewater from the oxidation chamber, and an enrichment factor S_(D) =237upon the utilization of water of output quality. In last instance, foundin the deuterium content of a total of 4 t of water; water of outputquality of 17.1 kg water. After the twelfth enrichment stage, obtainedfor deuterium is a degree of enrichment of S_(D) =2.711 and,respectively, 3.620. After the twelfth enrichment stage, there are onlyto be further processed 0.453 kg water/h.

The inventive enrichment process for deuterium and/or tritium in watercan also be utilized in an advantageous manner for the elimination oftritium-containing water, which is encountered during the cooling gaspurification of high temperature nuclear reactor installations andduring the reconditioning of fuel elements. The water which is removedfrom a cooling gas cleaning installation is then introduced directlyinto the carrier gas flow conducted to the primary side of the firstenrichment stage, as well as being introduced into the carrier gas flowon the secondary side as the material for the isotope exchange. As isshown hereinabove, in an installation having a plurality of enrichmentstages there can be obtained a concentration of the tritium in waterwhich is withdrawn from the cooling gas through the gas cleaninginstallation, wherein the quantity of water with the radioactiveimpurities which is to be finally stored water quantity, is to bereduced by the degree of enrichment. The described enrichmentinstallation can be preferably employed in connection with anarrangement for the separation of hydrogen and/or deuterium and tritiumfrom a cooling gas flow from high temperature reactor installations,which is described in the presently pending German Patent ApplicationNo. P 31 21 125.9. This arrangement includes gas cleaning chambers whichare arranged directly in the primary cooling gas circuit, and areequipped as are the exchange devices of the hereindescribed enrichmentinstallation, with exchange walls adapted for the permeation ofhydrogen. Withdrawn from the gas cleaning chambers is a carrier gas flowwhich contains deuterium and/or tritium removed from the cooling gascircuit of the nuclear reactor installation in an oxidized form. Thiscarrier gas flow can be introduced directly into the reduction chamberof the first stage of the inventive enrichment installation.

What is claimed is:
 1. A process for the incremental enrichment of deuterium and/or tritium in a material adapted for the isotope exchange of deuterium and tritium with hydrogen, comprising introducing and reducing water containing deuterium and/or tritium in a carrier gas flow while setting a hydrogen (H₂) partial pressure of maximum 100 mbar in the carrier gas flow; thereafter conveying the carrier gas flow along the primary side of an exchange wall adapted for the permeation of hydrogen; conveying a further carrier gas flow along the secondary side of said exchange wall, said further carrier gas flow containing the material adapted for the isotope exchange in the gas phase thereof; said process being conducted under such conditions as to induce said isotope exchange as a result of permeation through said exchange wall and to enrich the carrier gas on the secondary side with deuterium and/or tritium, and conducting off reaction products from the carrier gas on the secondary side formed subsequent to the isotope exchange of deuterium and/or tritium with hydrogen.
 2. Process as claimed in claim 1, wherein the material for the isotope exchange in the carrier gas flow on the secondary side comprises water or steam.
 3. Process as claimed in claim 1 or 2, comprising setting a temperature for the isotope exchange in the temperature range of between 100° and 300° C.
 4. Process as claimed in claim 1, comprising conveying the carrier gas flow along the secondary side of the exchange wall in counterflow with the carrier gas flow along the primary side of the exchange wall.
 5. Process as claimed in claim 1, comprising utilizing the same carrier gas on the primary side and on the secondary side of the exchange wall.
 6. Process as claimed in claim 5, comprising branching off a portion of the carrier gas flow from the primary side of the exchange wall, adding said material for the isotope exchange to said branched off carrier gas flow, and conveying said carrier gas flow portion to the secondary side of the exchange wall.
 7. Process as claimed in claim 1, comprising conducting the carrier gas flow on the secondary side over a catalyst subsequent to the addition of the material for the isotope exchange but preceding passing through the secondary side of the exchange wall, said catalyst accelerating the reaction between the material added and the hydrogen isotopes contained in the carrier gas flow on the secondary side.
 8. Process as claimed in claim 7, comprising introducing the catalyst on the secondary side of the exchange wall.
 9. Process as claimed in claim 1, comprising conducting the secondary carrier gas flow over a metal oxide preceding the addition of the material for the isotope exchange.
 10. Process as claimed in claim 1, comprising adjusting the hydrogen (H₂), partial pressure in the carrier gas flow on the primary side subsequent to reduction of the water contained in the carrier gas.
 11. Process as claimed in claim 1, comprising conducting the carrier gas flow on the primary side ahead and in the region of the exchange wall over a catalyst accelerating the atomization of the reduction products.
 12. Process as claimed in claim 1, comprising introducing water into the carrier gas flow on the secondary side adapted as the material for the isotope exchange, the content of deuterium and/or tritium in the water corresponding to the content of deuterium and/or tritium which is contained in the water introduced in the first enrichment stage on the primary side into the carrier gas flow.
 13. Process as claimed in claim 1, comprising reconveying the carrier gas flow streaming off the primary side of the exchange wall, subsequent to oxidation of the hydrogen carried along by the carrier gas and the separation of the water formed thereby, in a closed circuit to the inlet of the enrichment stage.
 14. Process as claimed in claim 13, comprising conveying the carrier gas on the primary side of an exchange wall adapted for the permeation of hydrogen, a material adapted for the oxidation of the permeating hydrogen being provided on the secondary side of the exchange wall, and conducting off the reaction products formed on the secondary side by a further carrier gas flow.
 15. Process as claimed in claim 13 or 14, comprising introducing the hydrogen-free carrier gas for adjustment of the hydrogen H₂ partial pressure into the carrier gas flow on the primary side subsequent to reduction of the water contained in the carrier gas. 